Multiple images of a distant quasar are visible in this combined view from NASA's Chandra X-ray Observatory and the Hubble Space Telescope. The Chandra data were used to directly measure the spin of the supermassive black hole powering this quasar.

For the first time, astronomers have directly measured the spin of a distant, supermassive black hole, according to an article published today by three University of Michigan researchers in the online journal nature.com.

Its speed? Half the speed of light. Because light travels at 186,000 miles a second — so fast that when you look at the full moon, the photons of light that are creating the image inside your head were bouncing off the moon less than a second and a half ago — that means this unimaginably heavy object is spinning at about 93,000 miles a second.

Supermassive black holes are millions or billions of times more massive than our sun and believed to be at the core of most, if not all, galaxies. There is one named Sagittarius A, for example, at the center of our galaxy, the Milky Way, 30,000 light years from Earth.

While astronomers have long been able to measure the masses of black holes — so named because they have such a gravitational pull that light cannot escape from them and therefore they are invisible, or black — determining their spins has been much more difficult.

Scientists have found ways to estimate spin, but until now their methods were indirect and relied on assumptions. But UM researchers Rubens Reis, Mark Reynolds and Jon Miller were able to precisely measure the spin of a distant supermassive black hole at the center of a quasar known as RX J1131-1231.

Quasars, among the most luminous and energetic objects in the universe, are made of matter falling into supermassive black holes. They give off energy and light at various wavelengths, including visible and X-ray, as their matter approaches the point, called an event horizon, at which no light or energy can escape the black hole's gravitational pull.

The black hole at the center of this quasar is about 7.7 billion years old and about 6 billion light years from Earth. That's 36 billion trillion miles away, which is 36 followed by 21 zeroes.

Normally, something that far away would be too faint to study. But the UM researchers were able to take advantage of gravitational lensing to do their measurements. Just as light bends through glass to make a bigger image for those who need glasses, it also bends from the force of gravity as it passes galaxies.

The lensing effect, and subsequent magnification, of light from quasar RX J1131-1231 as it passed by a giant elliptical galaxy on the way to us, gave Reynolds, Reis and Miller very detailed information that allowed them to come up with an accurate value for the black hole's rotational speed.

Because the black hole is spinning so fast, the researchers concluded that it has grown through cannibalizing entire galaxies and not just a diet of smaller objects such as nearby stars or interstellar gas.

Research for the paper, titled "Reflection From the Strong Gravity Regime in a Lensed Quasar at Redshift z=0.658," was supported by a grant from NASA.